Configurable with --transport_stream_offset_ms.
This is needed to compensate for possible negative timestamps in
inputs, which could happen on ISO-BMFF with EditLists.
Issue #112.
Change-Id: I0fce8766c9df2911b9bb859c1e54052a8ed2abfb
To remove the direct dependencies between packager.cc and the different
muxer implementations, this change remove the muxer factory to its
own file.
Change-Id: I4a1503c493f0f4d10a67e78461f96da3f4238944